Venting device for stylographic pens

ABSTRACT

A vent system for a tube writing pen wherein the vent consists of a longitudinally adjustable threaded stem extending within the writing fluid reservoir and venting at varying depths within the writing fluid. The upper end of the stem is open to atmospheric pressure through a venting channel defined in the pen housing.

United States Patent Danjczek et al.

VENTING DEVICE FOR STYLOGRAPHIC PENS Inventors: William E. Danjczek;Jean Pierre Leuenberger, both of Easton; Fortunato J. Micale; Ralph W.Wagner, both of Bethlehem, all of Pa.

Aaeigncc: Koh-l-Noor Rapidograph, lnc.,

Bloomsburg, NJ.

Filed: June 21, 1973 Appl No.: 372,388

Related US. Application Data Continuation-in-part of Ser. No. 185,020,Sept. 30, 1971, Pat. No. 3,741,668.

[56] References Cited UNITED STATES PATENTS 217,888 7/1879 Mackinnon401/258 226,924 4/1880 Nimmo 401/258 X 1,824,275 9/1931 Kellogg i401/258 1,937,660 12/1933 Luker 401/259 R9890 10/1881 Cross 401/258 XPrimary Examiner-Lawrence Charles [57] ABSTRACT A vent system for a tubewriting pen wherein the vent consists of a longitudinally adjustablethreaded stem extending within the writing fluid reservoir and ventingat varying depths within the writing fluid. The

U S Cl 401/258 upper end of the stem is open to atmospheric pressure IntCl. ll 43k 8/00 through a venting channel defined in the pen housingField of Search 401/258-260, 4 Claims, 4 Drawing Figures l l l i i 16 22I '4 l -26 l 1 I I I l 10 48 I I2 I 28 3, I l I I l l 1 24 J 11 f 30 nVENTING DEVICE FOR STYLOGRAPHIC PENS CROSS-REFERENCES TO RELATEDAPPLICATIONS:

A continuation in part of applicants METHOD OF VENTING A STYLOGRAPHICPEN (Ser. No. 185,020, filed Sept. 30, 1971 issued as US. Pat. No.3,741,668). The present application is directed to a modified structure,involving a simplification of parts.

BACKGROUND OF THE INVENTION Field of the Invention It is common to ventstylographic writing pens through a spiral venting channel which isbuilt into the nib. This venting channel communicates with the main inkreservoir via a hole in the upper end of the spiral venting channel. Thespiral venting channel is normally cut into the same surface that alsocarries the tightly pitched screw threads which are provided forscrewing the writing head into the body of the writing pen. Thisconventional arrangement has several consequences such as (a) twointersecting threads of different pitch, namely, the spiral ventingchannel and the screw thread must be cut into the nib, necessitatingthese additional production steps; and (b) the relatively short ventingchannel communicates with the outside air which may cause, even with theslightest neglect, the air to dry and block the venting channel,necessitating unscrewing the nib frequently for cleaning.

SUMMARY OF THE INVENTION According to the present invention, the ventingstem is axially reciprocable within the pen housing which has a lateralventing channel extending through its side. The venting stem has anhelical channel defined upon its exterior and a venting channelextending radially inwardly from the bottom of the helix into itsinterior chamber. The cleaning wire and lead weight are freely supportedwithin the interior chamber. The ink reservoir is mounted atop thehousing such that the ink flows downwardly into the interior chamber andthence outwardly of the pen through the tubular writing point.

As defined in the parent application, the rate of flow of the ink may beregulated by varying the positioning of the vent stem with respect tothe lower end of the writing point and according to the followingformula:

F magnitude of the hydrostatic head 1= density of the writing fluid gacceleration due to gravity 980 cm/sec.

r,, radius of vent stem bottom tip X distance between vent stem bottomtip and the lower end of the writing point.

y surface tension of writing fluid.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a perspective view of the pen housing supporting the tubularwriting tip at one end and the ink reservoir at the other end; and

FIG. 2 is a vertical elevation, partially in section showing the ventingchannel extending through the side of the lower housing so as tocommunicate with the DESCRIPTION OF THE PREFERRED EMBODIMENTS:

In FIG. 1 there is illustrated a lower pen housing 10, supporting awriting nib 30 through which extends tubular writing point 34. At theupper end of the housing ink reservoir 42 may be fitted upon a laterallyextending shoulder 36.

Lower housing venting channel 48 is defined in the sides of the housingso as to communicate with helical venting channel 14 inscribed in theexterior.

In FIG. 2 the lower pen housing 10 is more particularly illustrated asreciprocably supporting venting stem 12 having an open top 18, a helicalventing channel 14 communicating with helix 26 and a radially inwardly Iextending venting channel 28 which extends into the hollow interior ofstem 12. A conventional weight 40 and cleaning wire 42 (illustrated inFIG. 2.) fits removably within the stem such that the cleaning wire 42ex v tends into the tubular writing point 34 which is secured v theventing stem and an inner shoulder 46 may be employed to limit upwardmovement of weight 40. Venting channel 48 in housing 10 leads from inlet24 to lateral conduit 22 which communicates with lateral recess 14 suchthat the atmosphere is vented into the helix 26 and thence into thesupply of ink which flows through upper opening 44 past the weight 40and into the interior of venting stem.

As set forth in the parent application, the present venting systemenables control of the hydrostatic head at the writing tip end 34. Byincreasing the magnitude of the hydrostatic head, the rate of ink flowcan be regulated with greater accuracy for increased writing speeds thanhave been possible with conventional pens. This is of manifestimportance in computerized drafting where high speeds of writing arerequired.

As set forth in the parent application, applicant is able to define thehydrostatic head of the writing fluid at the point of contact with thewriting media in terms of the physical parameters of the pen and thephysical properties of the writing fluid. Thus, the magnitude of thetotal hydrostatichead determines with a high degree of accuracy thevelocity of flow of the writing fluid. The important practicalconsequence of the above is the prevention of the spontaneous formationof drops at the lower end of the writing tube. This constructionprovides for close control of ink flow independently of the amount ofwriting fluid in the reservoir, so long as the bottom end of ventingchannel 28 is immersed within the writing fluid. Applicant controls thedistance from the bottom end of channel 28 to the lower tip of thewriting tube and thereby the radius of curvature of the bubble 50 at theend of the writing tube.

In FIGS. 3 and 4 there is illustrated a modified form of the inventionwherein venting stem 50 supporting tubular writing tip 34 has alongitudinally extending upper body 52 and adjacent the nib a lateralventing channel 72 communicating with the ink-filled interior.

A plastic or like collar 54 having longitudinally threads or engraving56, as well as upper horizontal threads 66 and lower horizontal thread60, may be snap-fitted as to 58 to the exterior of body 52, defining atits upper end recess 62 for the support of an ink reservoir (notillustrated) and defining at its lower end recess 82 for supportingventing channel cover piece 82.

Within the top interior of body 52 there is defined inner shouider 64which may support a plug or cap securing the conventional weight 68 andcleaning wire assembly 70 in position.

Venting channel 72 communicates with a labyrinth 74 defined bycommunicating adjacent channels, such as 78 and 80. A vertical channel84 is defined at one end of the labyrinth and communicates with theiabyrinth top channel as at 76. Manifestly, the distance between thewriting tube tip 34' and the lateral venting channel 72 may be varied byrepositioning of the height ture and reciprocably positioned within saidhousing and between said venting channel and the interior of saidreservoir, said stem being vertically adjustible within said housing, soas to vary the height of said venting aperture interior and with respectto said writing tip;

F. a weight and cleaning wire assembly supported within said threadedventing stem, such that said cleaning wire extends reciprocably intosaid tubular writing tip.

2. A stylographic writing pen as in claim 1, said venting stem includingan helical exterior venting channel extending from the top to the bottomthereof and a radially inwardly extending venting aperture extendinginteriorly from the bottom of said helix.

3. A stylographic writing pen as in claim 2, said housing ventingchannel communicating with said venting stem helix.

4. A stylographic writing pen as in claim 3, said venting stern, saidwriting nib and tubular writing tip being vertically adjustable withrespect to said venting channel in said housing.

Where:

F magnitude of the hydrostatic head I density of the writing fluid 3acceleration due to gravity 980 cm/sec. r radius of vent stem bottom tipX distance between vent stem bottom tip and the lower end of the writingpoint.

y surface tension of writing fluid.

1. A stylographic ink writing pen comprising: A. a housing having aventing channel extending from the exterior to the interior thereof; B.a writing nib; C. a tubular writing tip having its lower end extendingthrough the bottom of said nib; D. an ink reservoir supported withinsaid nib and communicant with said writing tip; E. a threaded ventingstem including a venting aperture and reciprocably positioned withinsaid housing and between said venting channel and the interior of saidreservoir, said stem being vertically adjustible within said housing, soas to vary the height of said venting aperture interior and with respectto said writing tip; F. a weight and cleaning wire assembly supportedwithin said threaded venting stem, such that said cleaning wire extendsreciprocably into said tubular writing tip.
 2. A stylographic writingpen as in claim 1, said venting stem including an helical exteriorventing channel extending from the top to the bottom thereof and aradially inwardly extending venting aperture extending interiorly fromthe bottom of said helix.
 3. A stylographic writing pen as in claim 2,said housing venting channel communicating with said venting stem helix.4. A stylographic writing pen as in claim 3, said venting stem, saidwriting nib and tubular writing tip being vertically adjustable withrespect to said venting channel in said housing. F lg X - 2 gamma /rAWhere: F magnitude of the hydrostatic head l density of the writingfluid g acceleration due to gravity 980 cm/sec.2 rA radius of vent stembottom tip X distance between vent stem bottom tip and the lower end ofthe writing point. gamma surface tension of writing fluid.